Summer Soil Builder - Warm Season Green Manure
NOT to WA & TAS
Glycine max, Vigna radiata, Helianthus annuus, Helianthus annuus, Fagopyrum esculentum, Panicum miliaceum
Suitable for: All veggie gardeners (summer fallow), tropical/subtropical gardeners year-round, market gardeners, broadacre summer fallow, permaculture practitioners
Sowing rate: Garden beds: 50–80 g/sqm (1 kg covers 15–20 sqm). Broadacre: 40–60 kg/ha.
Season: Oct–Feb (temperate) or Sep–Apr (tropical/subtropical). Soil temp must be above 18°C. Hot conditions only. Optimum 25–35°C. Tolerates 40°C+—no frost tolerance. In tropical zones, sow year-round.
Contains: Soybean, Mung Bean, Sunflower Black & Grey, Buckwheat, Millet.
Every Australian gardener knows the frustration: you sow a green manure in late spring, and by January it’s cooked. Oats bolt, peas wilt, clover burns off. Your soil sits bare through the hottest months - exactly when it needs cover the most.
Our Summer Soil Builder solves this with six species that don’t just survive summer heat - they thrive in it. Every component has its optimum growth range above 25°C and actively grows at 35°C+.
Soybean is the nitrogen-fixing powerhouse of the tropics - capable of fixing up to 300 kg/ha of nitrogen in ideal conditions, with massive above-ground biomass that smothers weeds. Mung beans provide lightning-fast germination (3 days) and thrive in both heavy clay and light sandy soils. The dual sunflower varieties (black and grey-striped) send taproots down to depths of over 2 metres, physically breaking compacted layers while establishing mycorrhizal fungal networks that benefit your next crop. Buckwheat mines locked-up phosphorus and provides rapid pollinator support. And millet is the ultimate drought survivor - it produces biomass in conditions that would kill most other cover crops.
This is the opposite of our autumn–winter mixes. Every species here needs warmth to perform.
Sowing Instructions
1. Wait until soil temperature is consistently above 18°C (typically mid-October in southern Australia).
2. Remove spent winter/spring crops. Light cultivation to 5 cm depth.
3. Optional: soak soybean seeds overnight to speed germination.
4. Broadcast seed at 50–80 g/sqm. Cover large seeds (soybean, sunflower) to a depth of 2–3 cm.
5. Water in well. In hot conditions, water daily for the first week.
6. Mung and buckwheat emerge first (3–5 days), millet (5–7 days), soybean and sunflower (7–10 days).
7. Once established (3–4 weeks), these heat-lovers are drought-tolerant.
8. Allow to grow for 10–14 weeks. Slash at early pod/seed set and incorporate into soil.
9. Wait 3–4 weeks before planting your autumn–winter crops.
